Ladder jack



E. COBLE LADDER JACK May 10, 1949.

' 2 Sheets-Sheet 1 Filed Jan. 3, 1948 INVENTOR.

ERNEST L. COBLE BY ATTORNEY May1O, 1949.- 1.. COBLE 2,469,593

LADDER JACK 2Sheets-Sheet 2 Filed Jan. 3, 1948 re 1o 2 2 1 f .J

5 L 10 F16. 3 I l ill I I INVENTOR. gRNEsT L. COBLE ATTORNEY Patented May 10, 1949 .to The Star Welding & Manufacturing Company, Inc.,. Cleveland, Ohio, a. corporation. of.

Ohio

Application January 3, 11948 IS6flfl1'3ND. 407.-

3 Claims. (01. 248-238) This invention relates to a jack adapted to be mounted-on a ladder 'at 'desirableheights' at one side of a wall or other structure. Two -ofthese jacks areadapted to be mounted on spaced ladders at .thesame level and support ascaffold, on. which one or more workmen may-stand, walk orsit.

One object of the invention is to provide an improved jack of this type constructed toengage parts of a ladder to insure safety-to the workman and eliminate tipping, wobbl-ingor. vibration of the scaifold incident to movement ofithe Workman thereon.

Another object of the invention is to provide an improved .jack of. this type having a, supporting; member on which one end portion of the scaffold rests, which member -cooperates with;

the corresponding supporting member on the other. jack. to prevent tipping or distortion of the scaffold intermediate the. jacks incident to, the operations or traverseof the workman on thescafiold.

Another object of the invention is to provide animprovedjack of this type havingspacedpairs oi fixedly related supporting members arranged to readily; engage and disengage the ladder rungs and ladder side rails which differ in size andspacing.

.Another object of the invention is to provide an improved jack of this type the parts of which are constructed to adequately support heavy loads.

Another object of the invention is to provide an improved jack of this type consisting of a frame member adapted toengage a rung andside rails of a ladder and chains each adapted, to engage a ladder rail and another ladder rung, each chain having-a terminating hook member shaped to insure a positive connection with an intermediate chainlink.

A further object of the invention is to provide an improved jack of this type having a base member provided with supporting elements or devices adapted to. engage a rung and side rails of a ladder, converging side members and chains connected to the outer ends of the side members Fig. 1 is a fragmentary elevation: showing-two spac d ladd rs dei ks. a h emb(wiringv y invention mounted thereon and supporting a, scafiold.

Big. 2' is asection onthe-line 2-4 of Fig. -3.

Fig. 3.is,a,section on the line 33. of Fig. .2,

Fig. 4 is a section on; the line 4:-4;-o,f Fig. 3.

Figs. 5 and "-6- are sections on the lines 5-15; and 6e.6, respectively, .of F -ig.;2;

Fig. 7 is a view similar to Fig. -2, but showin the jack mounted on the inner side of a ladden Invthedrawin s, I indicates asanentirety, the jackmountedon aladder; A. As shown inEig. 1., two jacks I are shown, mounted on spaced ladders A, A, to support ascafiold B, the ladders: being related to a, wallpor other structure (not: shown), on which a; sign or other device is to bemounted orwhich is to be repaired, painted; or otherwise conditioned. Each jack 1 consists of a frame 2; of. V-shape (that is, forms. a sub.- stantially isosceles triangle) and a pair-of chains, 3,, 3,;l-ater referred to. The frame 2 is formed from sections of metalbars, each-disposed vertical-ly. and welded; into arigid assembly. The frame 12' consists of. the following: 4. indicates. a. base member extending beyond,- the opposite. outer sidfis -of the side; rails of. a, ladder -5,

indicatesa pair of converging side-members con-H nected at their inner ends to end portions of the base member 4". outer ends of the side; members -5sa-re rigidly connected together by a bolt or rivet -6;. A vertically disposed member- 1: is interppsed between the outer ends of the side memb rsfi: and-.secured her t by t t 6. The member 1- serves-as astop for the scaffold B: and, a connectingdevice for the outerends of the chains 3. shown the member 1; extends upwardly to a slightly above the plane of t upper surface of; the scaffold B, and the chains Spare connected by- :a link to the upper end. oi the memb r I so, as. to -clear the scaffold arrg l permit the latter to be pqfiitionedi and r mcvetd w thcut reasi th hains 3;. 8 indicat sHarlem n alside me r isp s u war lyvof h e memb rs 5. 5, a h, m m 8. being; connected. at its outer end to the ad jacent; side member 5; and to the adjacent outer of the haseimember 4 to reinforce the latter. suppl menta m ber 8- ext nd bey nd the remote or outer side of the base member 4, as shown at 8a, so as to overlap the adjacent side rail a for a purpose later set forth. 9 indicates a cross member disposed substantially midway the inner and outer ends of the side members and connected at its opposite ends thereto. The cross-member 9 co-operates with the base member 4 to prevent deflection of the Side members 5 laterally or downwardly between their opposite ends.

It, It], indicate a pair of members mounted on the base member and extending outwardly thereof and adapted to removably engage a selected rung b of the ladder A and co-operate with the base member 4 to connect and support the inner end of the frame 2 to the ladder. Each rung engaging member i0 is spaced from the adjacent extension 8a so that they may be disposed at opposite sides of the adjacent rail a, of ladders having rails variably spaced. Each member 10 is of inverted U-shape, its inner side leg being provided with an extension 10a which is welded face-to-face to the outer side of the base member 4. The intermediate or curvilinear portion lb of each member i9 is struck on a large radius, as compared to that of the ladder rung b, so that such portion will extend a considerable distance above the base member d and the outer leg of the member will be spaced a considerable distance from its inner leg. As shown, the curvilinear portions Hlb of the members it engage the rung b and the lower horizontal edge of the base member 4 engages the adjacent side edges of the ladder rails a to connect the inner end of the frame 2 to the ladder. tion of the rung engaging members 10, as above set forth, provision is made to (a) adequately space the fulcrum point of contact thereof with a ladder rung above the lower edge of the base member 4, (b) to provide for variable fulcrum points on curvilinear portions [6b arranged to engage rungs I) mounted in side rails a which vary in thickness (measured between their inner and outer side edges), when the jack is supported on the outer side of the ladder (see Fig. 2) or its inner side (see Fig. 7) and (C) facilitates the operation of mounting the frame 2 in position on the ladder A and its removal therefrom.

I 1 indicate a sill rigidly mounted on the frame 2 in a plane which bisects the angle formed by the side members 5, 5, and extending from the base member 4 to the member I. The upper surface of the sill H is disposed in a plane above and parallel to the frame 2 and is engaged by the end portion of the scaffold B to support it horizontally from side edge to side edge and out of engagement with the side members 5, while.

permitting it to sag perpendicularly due to the weight of the workman and/or equipment on the scaffold as shown in dotted lines in Fig. 4. Accordingly, danger of the scaffold engaging the side bars 5, which, being disposed at an inclined angle, would cause wobbling, distortion or inclination of the scaffold, is entirely eliminated and any mishap to the workman or equipment on the scaffold is likewise avoided. The sill H also reinforces the frame from end to end.

By preference I provide two chains 3 each adapted to be wrapped around one of the rails or and above an adjacent rung 13 disposed above the rung b engaged by the frame 2. In this arrangement the chains 3 co-operate with the memher a and members II] to support the outer end of the frame 2 and hold the latter against swing- By the form of construcing movement in its plane. The outer end of each chain 3 is provided with attaching device l2, one end of which is provided with an eye lZa engaging the terminating link of the chain; the opposite end of the device I2 is provided with a hook the entrance opening of which is of a predetermined size to receive one side bar of a link, so that the hook cannot be engaged with the chain in any other manner. This form of hook insures its safe connection with an intermediate link of the chain 3, as shown in Fig. 6 and eliminates carelessness on the part of the workman in making such connections in mounting the jack on a ladder.

What I claim is:

1. A ladder jack for a ladder comprising a frame having a base member adapted to engage the ladder rails and extending beyond the opposite outer sides thereof, converging side members connected at their inner ends to said base member intermediate the ends thereof and connected together at their outer ends, a supplemental side m mber connected to the outer side of each of said converging side members intermediate its opposite ends and the adjacent outer end of said base member and provided with an extension extending outwardly of said base member and adapted to be disposed in overlapping relation to the outer side of the adjacent ladder rail, rung engaging members secured to the outer side of said base member inwardly of the ladder rails and extending upwardly and outwardly from said base member for engagement with a ladder rung and arranged to co-operate with said base member to support the latter in engagement with the ladder rails, and chains connected at their inner ends to the outer ends of said converging side members, the outer end portion of each chain being adapted to be wrapped around one of the ladder rails in engagement with a rung above the rung engaged by said rung engaging members.

2. A ladder jack as claimed in claim 1 wherein a vertically disposed member is connected at its lower end to the outer ends of said converging side members and extends upwardly therefrom and its upper end forms a connection for the inner ends of said chains.

1 3. A jack as claimed in claim 1 wherein is provided a sill connected at its opposite ends to said base member and the outer ends of said converging side members and extending in a plane to bisect the angle formed by the latter members, the upper surface of said sill, from end to end thereof, being in a plane above and parallel to the upper surfaces of said converging side members.

ERNEST L. COBLE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 881,996 Block Mar. 17, 1908 984,059 Zinsmayer Feb. 14, 1911 1,228,868 Anderson June 5, 1917 1,565,483 McLaren Dec. 15, 1925 

